Drafting pen



Dec. 20, 1966 M, B. YOUNG DRAFTING PEN Filed May l'. 1964 K wm. ,www mm, mm mm. WQ /4/ fe/@ l i? ilfl; a @ma E B N x llll ...1|!.l|, !l\|||x 1% V L m /44 @n m w w m WN. NN QN M /f um Nv mw M Q w M l l! mm w I m.. ltwi i f wn hw WN United States Patent() 3,292,595 DRAFTING PEN Marshall B. Young, Danbury, Conn., assigner to Eagle Pencil Company, Danbury, Conn., a corporation of Delaware Filed May 1, 1964, Ser. No. 364,202 2 Claims. (Cl. 1Z0- 44) This invention relates to the art of writing instruments and more particularly to `drafting pens.

As conducive -to .an understanding of ythe invention, itis 4noted that drafting pens are often used to draw lines on sheets or paper that is very abrasive and where this causes the point of the drafting pen to wear down quickly, the line drawn by the pen broadens so that the pen is no longer usable, requiring the draftsman to either insert a new writing point in the pen or replace the pen, which is time consuming and costly where replacement must be done frequently.

The problem of Wear is even more pronounced when thin lines must be drawn as a thin point required 'for this purpose lis generally more subject to Wear.

In addition, where the point rapidly broadens, the precision of line width required by the draftsman cannot be readily controlled so that it takes longer to make a given set of drawings and even with extreme care, any given line can vary in width along its length which is undesirable.

In order that the draftsman -c-an readily locate the position of the line that is being drawn, it isv essential that the tip of the writing point protrude suiciently from the body of the Writing instrument so that it is visible in use.

Where, to make a Writin-g point that is able to Withstand the wear caused by abrasive drafting material, a jewel such as a ring of sapphire or such as synthetic corundu-m, is used as the Writing point -or tip, Vdue to the diiculty lof forming such a jewel with a relatively thin Wall, in the lorder of say .004 of an inch required to form a thin line of lapproximately .008 yof an inch, the jewel tip is unsatisfactory Ifor many drafting (requirements. In addition, where the jewel is positioned in a socket and is held in position as by swedging the side wall of the socket against the side wall of the jewel, if the wall thickness of the jewel could be made suciently small to provide the desired writing line width, unless extreme tolerances were maintained and extreme c-are was taken in manufacture which would be impossible for lange scale economical commercial production, the pressure of the swedging action woul-d cause Adestruction of the jewel.

It is accordingly among the objects of the invention t-o provide a drafting pen which has a writing point that may readily be fabricated at low cost, which is strong and durable and will have extremely lon-g life even with use on the relatively abrasive surfaces Inormally employed by draftsimen, which will make a relatively -thin ink line of constant width which may be as narrow as .008 of an inch even after long Iuse, and the point of which may readily be seen by the draftsman when in drawing position to facilitate location of the lines -to be drawn.

Another yobject is to provide a nib for a drafting pen which incorporates a writing point of the -a-bove type and which may readily be removed :from the drafting pen for replacement.

According to the invention, the drawing pen comprises a barrel which `defines the ink reservoir and which has a threaded yopening at one end in which the nib is removably inserted. The nib comprises an externally threaded hollow casing, the bore of which is of :reduced di-ameter at its outer end to receive the end of a tube made preferably of stainless steel.

The end of the tube has an enlarged bore diameter ICC defining a recess .for a hollow t-ip of metallic carbide of length preferably slightly less than twice the depth of said recess, the tip being secured in the recess as by soldering the end of the tube to the adjacent portion of the hollow tip.

In the accompanying drawings in-Which is shown one of various possible embodiments of the several features of the invention,

FIG. 1 is a plan view lof a drafting pen,

FIG. 2 is a perspective view on Ian enlarged scale oli the nib,

FIG. 3 is a longitudinal sectional view on a greatly enlarged scale with parts broken away oct the writing end of the pen, and

FIG. 4 is a longitudinal sectional view of the tip of the pen.

Referring now t-o the drawings, the drafting pen comprises .a barrel 11 which delines the ink reservoir and handle or -grip portion of the pen and which may be of any suitable material such as plastic for example.

Positioned in thebarrel .11 is a conventional filling plun-ger 12 which can be retracted by rotating a knob .13 formed at the end of the pen to -draw Iink into the reservoir.

vAs this construction is well known in the art and per se dorms no part lof the present invention, it will not be further described.

The nose end 14 of the barrel 11 is internally threaded as at 15` to receive the writing nib 16 of the present invention. As shown in FIGS. 2 and 3, the nib 16 comprises a cylindrical body portion 17 externally threaded as at 18 so that it may be screwed into the internally threaded portion 1-5 of the nose end 14 of the barrel, the outer end 19 of the nib .15 being tapered as shown. l

The threaded body portion 17 has -a plurality of circumferentially spaced longitudinal :grooves 21 leading from the reduced `diameter portion 22 between ythe end 19 and the adjacent threaded portion 18 to a passageway 23 leading into the bore 24 of the hollow nib 16 which provides a vent for the ink in the reservoir.

The tapered end 19 yof the nib has a bore 25 of reduced diameter in communication with the langer .diameter bore 24. Positioned in said bore 25 as by :torce fit, is the enlarged diameter end 28 of a tube 29 preferably of stainless steel which has a relatively small diameter bore 31 therethrough of approximately .009 of an inch.

The portion 32 of tube 29 protruding from the tapered end 19 of the nib 16 is of reduced diameter of approximately .O37 of an inch and the outer end of the tube has an axial recess 33 therein of diameter approximately .017 of an inch and of depth approximately .045 of an inch thereby providing the recess with 4a wall having a wall thickness of approximately .010 of an inch.

Positioned in said recess is a hollow tube or tip 34 of metallic carbide, preferably tungsten carbide of diameter substantially equal to the diameter of said recess 33, Le., .017 'of an inch and having a bore diameter 30 the same as that of the bore 31 of tube 29, i.e., .009 of an inch. Y

Thus, the wall thickness of the hollow tip is approximately .004 of an inch.

The tip 34 is approximately .062 of an inch in length so that it protrudes from the end 35 of the tube 29 by approximately .017 of an inch and the rim 36 of the outer end of the tip 34 is rounded as shown.

The tip 34 is retained in the recess 33 as by soldering the end 35 of the tube 29 to the adjacent portion of the tip 34 as at 36.

Positioned in the bore 24 0f the nib 16 is a substantially cylindrical weight 37 of diameter slightly less than that of the bore 24 to define an annular passageway 38 for flow of ink from the reservoir defined by the barrel through the aligned bores 31, 30 of the tube 29 and tip 34 which form a capillary passageway. The weight 37 is of length less than that of bore 24 and is retained there-` in by a hollow externally threaded screw 41. The outer end 42 of the Weight 37 has one end of a feed wire 43 secured thereto, the .feed wire extending through the aligned capillary bores 31, 30 of the tube 29 and the tip 34 and protruding just slightly beyond the tip 34 when the pen is in vertical position but spaced from the writing surface.

With the construction above described, the ink will ow in conventional manner through the small diameter capillary bores 31, 30 when the tip 34 is pressed against the writing surface in use.

Due to the hardness of the tungsten carbide tip 34, it will have relatively little wear even after long use. By reason of the thin wall of the tip 34 which is lin the order of `004 of an inch, `a thin line in the order of .008 of an inch or less can be drawn when the drafting pen is held at the usual inclination.

As no stress is placed on the thin wall of the tip 34 to retain it is the recess 33, since such retention is by soldering, there is no danger lof breaking of the relatively brittle tip during manufacture. Furthermore, the fact that a substantial portion of the tip 34 is retained in the recess 33 provides sufficient strength to prevent breaking or bending of the tip 34 even when pressure is applied thereto in use.

By reason of the fact that the tip 34 is elongate and extends considerably from the end 35 of the rigid supporting tube 29, the draftsman will be able to clearly see the tip of the drafting pen in use so that he can readily locate his lines.

It is to be understood that the dimensions above set forth are merely for purposes of illustration and may be varied slightly so long as the wall thickness of the tip 34 is maintained small enough to provide the line thickness desired.

As many changes could be made in the above article, and many apparently widely different embodiments of this invention could be made without departing from the scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus decribed my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A drafting pen comprising an ink barrel, a capillary Writing point mounted on the end of the barrel in cornmunication with the interior thereof, said writing point comprising a tubular support having an axial recess in` one end, a tubular tip having one end positioned in` said recess and protruding therefrom by an amount slightly less than the depth of said recess, said tip being formed of tungsten carbide, the end of said tubular support being bonded to the adjacent portion of said tubular tip, the bores of `said tubular support and tubular tip being longitudinally aligned and of substantially the same diameter to form-an elongated substantially continuous capillary channel.

2. The combination set forth in claim 1 in which said bonding comprises a solder joint.

References Cited by the Examiner UNITED STATES PATENTS 2,206,615 7/ 1940 Pfanstiehl et al. 120-109 2,214,494 9/1940 Wallace 120-44 2,228,235 1/ 1941 Pfanstiehl 120-109 2,600,426 `6/ 1952 Paul 120-44` 3,020,884 2/ 1962 Riepe 1Z0-44 l FOREIGN PATENTS 860,387 2/1961 Great Britain.

LAWRENCE CHARLES, Primary Examiner. 

1. A DRAFTING PEN COMPRISING AN INK BARREL, A CAPILLARY WRITING POINT MOUNTED ON THE END OF THE BARREL IN COMMUNICATION WITH THE INTERIOR THEREOF, SAID WRITING POINT COMPRISING A TUBULAR SUPPORT HAVING AN AXIAL RECESS IN ONE END, A TUBULAR TIP HAVING ONE END POSITIONED IN SAID RECESS AND PROTRUDING THEREFROM BY AN AMOUNT SLIGHTLY LESS THAN THE DEPTH OF SAID RECESS, SAID TIP BEING FORMED OF TUNGSTEN CARBIDE, THE END OF SAID TUBULAR SUPPORT BEING BONDED TO THE ADJACENT PORTION OF SAID TUBULAR TIP, 